Safety and Effectiveness of Letermovir in Allogenic Hematopoietic Stem Cell Transplantation Recipients: Interim Report of Post-marketing Surveillance in Japan

OBJECTIVE: Since May 2018, a 6-year post‑marketing surveillance (PMS) has been underway to evaluate the safety and effectiveness of letermovir for cytomegalovirus (CMV) prophylaxis in Japanese patients with allogenic hematopoietic stem-cell transplantation (allo-HSCT). The interim PMS data for 461 patients collected as of March 2021 are reported in this publication. METHODS: The case report forms (CRFs) were drafted in part by the Japanese Data Center for Hematopoietic Cell Transplantation (JDCHCT) using data elements in the Transplant Registry Unified Management Program (TRUMP) and sent to individual HSCT centers to decrease burden of reporting. These CRFs were completed by physicians in the respective HSCT centers and sent to MSD K.K., Tokyo, Japan. RESULTS: Allo-HSCT recipients prescribed with letermovir for CMV prophylaxis were included across 136 centers in Japan between May 2018 and March 2021. Safety and effectiveness were assessed for 460 and 373 patients, respectively. Of the patients in the safety analysis, 13.9 % experienced adverse drug reactions, the most frequent of which were renal impairment (2.2 %) and nausea (1.7 %). Among patients in the effectiveness analysis, the overall CMV antigen positivity rate was 21.2 % at Week 14 and 37.5 % at Week 24 after allo-HSCT. CONCLUSIONS: Interim data from this largest of real-world studies confirm the safety and effectiveness of letermovir for CMV prophylaxis in Japanese allo-HSCT recipients. Given the limited data on Asian patients for letermovir use, this survey will provide valuable information for medical decision-making in routine clinical practice, serving as a vital supplement to the results obtained from clinical trials. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40261-021-01096-5.